Running Room Ultimax Velocity Pro is Ultra Thin and has a foot hugging fit. It is knit with Stretch nylon for durability and X2O Acrylice which absorbes moisture and then evaporates. This sock keeps your feet dry, comfortable and most of all….Blister free! If you are looking for a sock that makes you feel like you aren't wearing a sock in your running shoe, then this style is for you!